All You Need To Know About The Pre Build Costs of an Extension…

Extension Pre Build (Initial) Costs

Never mind what you are going to pay your builder to construct the blessed extension, have you considered how much you may have to shell out on “professionals” before he removes the first sod?

Here, professional is used in the true sense of the word. Even planning officers have been to university nowadays, even if you might think they were away the day the common sense classes were held.

So what extras (and in what order) will you probably end up paying for?

The following have main articles dedicated to them elsewhere on the site. To gain a fuller understanding we recommend you read them as well.

Planning (see planning applications)

The whole area of planning can be a minefield. We consulted a recently retired chief planning officer in order to write our main article. He had problems unravelling the process for us. At best it’s a see saw process, if you have a go yourself and are successful it will cost about £150.

If you employ a “planning professional” they will charge around £250 on top of this.


Architect (see architects)

Who may also be your “planning professional”. You know what these lovvies do. You need his doodlings in order to get an idea of what he’s decided you really want. The planning department needs them in order to reject the first draught. The builder needs them to see if the stainless steel spiral stair will get through the door. The structural engineer needs them to determine the size of his fee.

An architect who only visits the site once to look at the lie of the land before he starts drawing, will charge about £350 for a small extension.


Structural Engineer (see structural engineer)

What do I need one of them for I hear you ask? Well there’s a slim chance you may not but if you plan to get into your extension through anything bigger than a normal doorway (it may be open plan with the rest of the house for instance), you will. Openings have weight above them, this needs supporting. The architect will dictate what type of support is needed (steel, concrete, wood) but the engineer is required to calculate how strong it has to be.

For this he will charge around £250.


Building Regulations (see building regulations)
We’re nearly at the end! Planning tells you “if”. Architects and engineers tell you “how”. Building regulations officers tell you (or to be more precise, your builder) “carry on”. Their job is to inspect the job as it progresses and give the “ok”.

They used to be “supplied” by the local authority but suitably qualified private individuals can now undertake the work.

They charge nearly £500.


Party Wall Surveyors

If you live in a semi or a terrace, a party wall separates you from that lot next door. If your extension has to be supported in part by this wall, by law you will have to inform your neighbours. If they have any sense they will want to know the structural effect of this. They may then not understand the evidence you present, or might just get bloody minded.

In any event, if you end up with a row on your hands you will need a mediator, possibly one appointed by them and guess who will have to pay for it all!

He will charge around £250. If he needs to engage a structural engineer, that could be another £250.